1. Field of the Invention
This invention relates to a closure of the type which may be applied to a helically threaded finish of a glass or rigid plastic container by a press-on action, but which may be normally removed from the finish of the container only by a twisting action. More particularly, this invention relates to a press-on, twist-off closure that is constructed and arranged to optimize torque that is required to remove the closure.
2. Description of the Related Technology
Closure caps of the press-on turn-off variety for glass or hard plastic containers are known and are in wide commercial use. Such closure caps provide a hermetic seal with the container for packing and holding hot-fill or cool food or beverage products such as baby food. Typically, such closure caps have a metallic body including a top panel and a depending skirt portion, both of which are lined with a deformable gasket material. This construction permits the closure caps to be pressed vertically downwardly onto the mouths of glass containers that are provided with circumferential bands of thread formations. The gaskets are formed of suitable plastomeric compounds such as plastisols, which are capable of taking cold flow sets under compression and thereby form thread formations which compliment or mate with those on the neck of the containers. The closure cap may then be removed by a consumer by twisting it like an ordinary twist off closure to unscrew it from the container.
Conventional closure caps of the press-on turn-off variety tend in many cases to be difficult to open for some consumers because of the amount of torque that is required to remove the closure cap from the container. In an attempt to address this issue, certain closure caps that are in commercial use are provided with equally spaced flutes of raised gasket material on the inside of the depending skirt portion of the closure, which is intended to reduce the amount of contact surface between the gasket and the container threads. In actual practice, however, such closures do not always provide the desired removal torque. The inventors have determined that this is due in part to the fact that the equal and symmetrical spacing of the flutes provides too much contact with the embedded glass container threads.
A need exists for an improved closure cap of the press-on turn-off variety that is configurable so as to permit a significant reduction in the amount of torque that is required to remove the closure cap from a container, without compromising the quality of the hermetic seal that is formed with the container during packaging.